Diverticula are small, bulging pouches that can form in the lining of a digestive system, according to Mayo Clinic. They are common after the age of 40 and rarely cause problems.

However, they can become inflamed or infected and cause colon pain, fever and nausea.

There have been no official updates on McCain’s health from his office since the surgery, but his son-in-law, Ben Domenech, said last month that the ailing senator was “doing well” as he spends time at his Arizona home with family.

McCain also received visits from many of his friends and politicians in recent weeks, including former Vice President Joe Biden, Sen. Lindsey Graham of South Carolina, retired Connecticut Sen. Joe Lieberman and Arizona Gov. Doug Ducey.

While the Republican has not been seen in public lately, he has made his presence known, commenting on the latest news through his Twitter account and press releases, publishing his memoir, “The Restless Wave: Good Times, Just Causes, Great Fights, and Other Appreciations” and being featured in an HBO documentary.

Meghan McCain said she was grateful to those who have helped her get through the “painful” process.

“The thing I’ve learned most through this process is there’s almost no one that you can meet in life who hasn’t had an experience with cancer, unfortunately,” she added.

“And people are very compassionate and very understanding. It’s been a nice silver lining of something that’s been very painful.”